The use of lambskin, sheepskin, or wool rollers for applying paint to a surface has been known for many years. Some of the first painting rollers were formed from sheepskin, napped wool or wool felt due to the availability and suitability of the material, and the lack of alternatives. The advent of synthetic fibers resulted in the availability of suitable synthetic paint rollers that were cheaper and more readily disposable, however some painters still preferred wool to other fibers.
The purpose of the roller material is to absorb paint quickly and provide relatively even paint distribution throughout the roller material and, thus, smooth paint application onto a surface. The ultimate purpose of the paint roller is to provide fast and even coverage of a surface with the desired paint. A painter's choice of roller material would be based, in part, on how well the material met this purpose. Ease of cleanup, including washing effort, drying time, or disposability, also played a part in the painter's decision.
Traditional wool and synthetic paint rollers are available in a variety of nap lengths chosen depending on the surface to be painted. Smooth surfaces are usually painted with short napped rollers, 1/4 inch in length, that provide a smooth and even paint application. Surfaces with some texture or roughness are usually painted with medium napped rollers, 3/8-1/2 inch in length. The longer nap length facilitates paint application into the crevices as well as the raised areas of the rougher surface. Rough surfaces require long napped rollers, 3/4 inch in length, to accommodate the variations in surface texture. For extremely rough surfaces, very long napped rollers in length of 1 to 11/4 inch can be used. For most normal or average wall surfaces, shorter napped rollers, i.e., 1/4-1/2 inch, are usually preferred due to their even absorption and smooth application of paint without unwanted surface effects, such as streaking, dripping, texturizing, or pattern formation.
On the other hand, in situations in which a decorative, texturized or patterned finish is desired, a number of other types of paint rollers have been developed. These include: embossed rollers; open webbed coarse filament, fiber or stranded material rollers; pile fabric, carpet fabric, and mohair fabric rollers; and plain and patterned foam rollers. In addition, attempts have been made to simulate the effect of, while simplifying the application of other traditional surface finishes, such as sponging, rag rolling, stippling, and marbleizing, by attaching rags, flaps or other projections onto a roller surface.
In addition to paint rollers, paint pads have been developed to provide an alternative tool for producing decorative finishes. Pad materials, such as foam, wool, sponge, fibers and other textured materials, are capable of producing finishes that are very pleasing and often substantially similar to the traditional surface finish techniques described above. For painted finishes requiring multiple colors or characteristics, paints are applied sequentially or, in some cases, simultaneously with the use of two or more pads at the same time. Producing a decorative finish by pad application, although effective, tends to be slower and more physically taxing than paint roller application methods.
With the increase in interest in do-it-yourself home application of surface finishes, instead of the traditional use of professional decorators or painters to achieve the desired effect, the need for ever simpler, faster and more cost effective decorating tools has also increased. Although numerous tools are currently available, as discussed above, each has its drawbacks and shortcomings.